One of the remaining animals at Winona’s Prairie Island Deer Park rested last week. After fears that an outbreak of chronic wasting disease at a local farm had spread to the deer park, three other deer were euthanized and tested.
After fears that an outbreak of chronic wasting disease at a local farm had spread to the deer park, three other deer were euthanized and tested. The results were negative.

Chronic wasting disease in Winona County

(3/12/2018)

by CHRIS ROGERS

Three deer from Winona’s Prairie Island Deer Park were euthanized and tested for chronic wasting disease (CWD) late last month. The good news: those results were negative. The bad news: elsewhere in Winona County, all of the deer at a rural deer farm tested positive for CWD. It is the first confirmed occurrence of the disease in Winona County.

Sometimes nicknamed the “zombie deer” disease, CWD is similar to Mad Cow Disease. It attacks the brains and nervous systems of deer and other animals in the cervid family, including moose and elk. The disease is caused by malformed proteins called prions. It is always fatal, and there is no treatment or vaccine. CWD has been spreading through deer populations across the U.S., including Iowa and Wisconsin, but outbreaks in Minnesota have, so far, been limited. There was an outbreak at an elk farm near Pine Island, Minn., in 2010, and a year later, a wild deer near the elk farm tested positive for CWD. The first outbreak in Fillmore County was discovered near Preston in 2016, and since then, 17 wild deer from Fillmore County have tested positive for CWD. Most of those were within a few miles of the original outbreak near Preston, but one was found just south of the Winona County line. Through a combination of mandatory checks of carcasses during hunting season and a special hunt this January specifically to test for CWD, the Minnesota Department of Natural Resources (DNR) has been monitoring wild deer in Winona County and has yet to discover the disease in wild deer in Winona County.

Winona County’s first case of CWD

The Minnesota Board of Animal Health (BAH) discovered CWD in a small herd of captive deer at a farm in Winona County this winter. The farm is one of several deer and elk farms in Winona County, and like all deer farms, it is supposed to submit samples from every single carcass to be tested for CWD. In November 2017, one deer culled from the herd tested positive for CWD, BAH Assistant Director Linda Glaser explained. The BAH quarantined the farm immediately, and after a second culled deer tested positive for CWD, the BAH and the U.S. Department of Agriculture (USDA) euthanized the remainder of the small herd — seven deer. “All the animals were infected,” Glaser reported.

The farm is under ongoing quarantine: it cannot keep any deer or other cervids for the next five years and it must maintain its fencing around the former deer enclosure. If wild deer get into the enclosure — or if they already have — they could be contaminated by prions in the soil. Feeders and other wood objects within the enclosure will be burned. However, Glaser explained, “Prions aren’t really something that you can clean and disinfect … We try to clean to our ability, but prions aren’t readily killed by that kind of thing.”

Winona deer park not infected

The BAH checked the Winona County farm’s records to see whether any captive deer had been moved in or out of the farm within the past five years. “This farm is small, and they hadn’t had a lot of movement, but we saw they moved three does over to the city of Winona park,” Glaser explained.

Once the BAH discovered that, Winona’s Prairie Island Deer Park was quarantined, and the three animals that the city had acquired from the farm were euthanized and tested for CWD on February 21. “When we found out, obviously we were concerned because of the emotions involved with chronic wasting disease in the whitetail population,” Winona Public Works Director Keith Nelson stated. By emotions, Nelson explained that he meant local hunters’ concerns about the disease spreading. “Chronic wasting disease is very destructive on the wild population where it’s prevalent, and hunters are very emotionally involved in having a healthy, abundant whitetail population. We don’t want to be adding to the disease in any way or hurting the whitetail population,” he stated.

Fortunately, none of the three deer that had come from the farm to the deer park had CWD. That means the remaining three animals at the deer park do not have be put down.

How did farm’s infection start?

Exactly how the Winona County farm’s deer herd was infected in the first place is unclear. CWD can travel by humans transporting captive deer or elk between farms, by humans transporting deer carcasses, and by deer themselves roaming around. The first option seems unlikely in this case; the second two are possibilities.

Because the three deer were moved from the farm to the city park a couple years ago, the negative test results at Prairie Island helped Glaser narrow down the possible sources of the infection. There was only one new animal that had been brought into the farm’s herd within the last five years, she stated. That animal was subsequently sent to the deer park, and it tested negative for CWD. So the infection at the farm had to be relatively recent, Glaser concluded. “We believe this introduction had to be two years ago or less,” she said.

Wild deer might have introduced CWD to the herd. Acccording to Glaser, a tree had fallen on a portion of the fence at the deer farm, bringing down the fence height considerably. That — or another weakness in the fence — could have allowed infected wild deer to enter the pen.

Alternatively, deer carcasses might be the cause. The deer farm owner is also a taxidermist, and if he worked with infected carcasses, CWD prions could have spread to his herd. “That’s certainly a possibility,” Glaser said.

Has the infection already spread?

The Star Tribune reported this week that the fence around the Winona County deer farm had been sagging for years, and that BAH inspectors failed to identify and correct the problem. If that is true, it means that captive deer could have escaped or wild deer could have gotten into the enclosure.

In an interview, Glaser stated that the tree fall that damaged the fence had not yet occurred when BAH inspectors last visited the farm, in October 2017. She added, “We do not have any records of escapes from this herd, and I believe [the farm owner] that that hasn’t happened.”

“I read the [Star Tribune] article, and how the fence was out of compliance,” Cornicelli said. “Does that increase risk? It kind of does.”

Cornicelli hopes wild deer didn’t jump into that enclosure, grab a bite to eat, get infected, and jump out. He has some reason to be optimistic. The DNR has been doing extensive surveillance of CWD in Winona County, and it hasn’t gotten any positive results yet. “The fact that we have done quite a bit [of testing] already, keeps me a little bit hopeful that it hasn’t spilled out into the wild deer.”

Cornicelli said that the DNR will do more testing of carcasses in Winona County during hunting seasons in the fall, but the DNR will not drastically change its CWD management efforts in Winona County. “We’re not going to go out guns a-blazing around the deer farm,” he said. If the DNR does find CWD in wild deer in Winona County, that could change, he added.

Minnesota can slow the spread of CWD, but with significant outbreaks in Iowa and Wisconsin, Minnesota probably cannot stop the spread, Cornicelli said. “Our goal has been to do what we can to eliminate the disease in wild deer, and that becomes increasingly difficult as time goes by because our future is right across the river in Wisconsin,” he stated. “The future is not good, and we are trying to do what we can to not be like that,” Cornicelli stated.